Coated webs are used in a multitude of commercial and consumer products. A single example is batteries, some of which are constructed from a web coated with a conductive material and wound into a roll or stacked into a number of laminated layers. See, e.g., U.S. Pat. No. 5,360,684, among others.
Films coated onto webs often suffer from different thickness across the width of the film, especially at the coated film edge. If no effort is made to control the thickness or cross-sectional profile of the edge, an edge of a coated material will generally taper off in a gradual slope from the thickness of the bulk coating, to zero thickness.
Undesirable results of a tapered edge will result with the particular effect being dependent on the application that the coated material is designed for. In batteries constructed of multiple wound or stacked layers, undesirable possibilities of an uneven or tapered edge result upon placing the coated substrates into a layered configuration. An “edge effect” can result because the capacity of the tapered edge of a coated cathode is used up faster than the capacity of the bulk coating. This edge effect results in a non-uniform charge density, may cause hot-spots or shorts in the battery, and can ultimately result in a reduced cycle life.
Methods of attempting to control edge thicknesses and profiles are various, some including the use of dams or air or water systems designed to remove a coated film layer from a coated substrate.